1. Field of the Invention
The present invention relates to a phase adjusting method and apparatus, and in particular to a phase adjusting method and apparatus for adjusting data transmission (propagation) times across a plurality of systems between a station end device—an antenna end device in a wireless (radio) base station.
2. Description of the Related Art
In a wireless base station, for example, data from a station end (side) device are transmitted through an antenna end (side) device to a terminal (mobile terminal), and data from the terminal are received by the station end device through the antenna end device, where a transmission/reception system for the data forms a dual system consisting of e.g. a working (act) system and a protection (standby) system in order to continuously obtain data of a system free from deterioration.
Therefore, it is required that data reception timings at the station end device upon performing a data change (transfer) between both systems are concurrent, so that delay times from the station end device to the terminal should be the same between both systems. In this case, it is known that between the antenna end device and the terminal, little delay time difference occurs between the working system and the protection system because both systems have substantially the same route or distance, so that it is understood that the data change between the working system and the protection system can be smoothly done by making the data transmission times between the station end device and the antenna end device identical with each other between both systems.
Also, in order to specify the position of the terminal, the distance from the antenna end device to the terminal has only to be measured. In order to measure the distance from the antenna end device to the terminal, provided that a data change is performed between the working system and the protection system, the phases of both systems are adjusted or synchronized when data transmitted from the station end device as described above are returned through the antenna end device and the terminal to and received by the station end device. Then, by, subtracting a delay time of data transmitted from the station end device through the antenna end device and returned to the station end device from the entire delay time of the data transmitted from the station end device through the terminal and returned to the station end device, the delay time from the antenna end device to the terminal can be measured whereby the distance from the antenna end device to the terminal can be determined. This enables the position of the terminal to be specified.
A prior art example of a wireless base station performing such a phase adjustment is shown in FIG. 8. In this prior art example, a station end device 50, an optical transmission line 2 and an antenna end device 3 compose a wireless base station, in which the antenna end device 3 is further connected to a terminal 5 through a wireless transmission line 4.
The station end device 50 comprises a FIFO (First-In-First-Out) 51 forming an interface portion serving to transmit a main signal frame to the optical transmission line 2, and a FIFO 52 forming an interface portion for receiving a main signal frame from the antenna end device. The FIFO 51 further includes a FIFO 51W for a working system and a FIFO 51P for a protection system, in which the FIFO 51W is connected to an antenna end device 3W for the working system forming the antenna end device 3 through a down optical transmission line 2_DW for the working system, and the FIFO 51P for the protection system is connected to an antenna end device 3P for the protection system forming the antenna end device 3 through a down optical transmission line 2_DP for the protection system. These antenna end devices 3W and 3P are adapted to be connected to the terminal through the wireless transmission line 4 which can be substantially regarded as the same transmission line.
Also, the FIFO 52 is composed of a FIFO 52W for the working system and a FIFO 52P for the protection system, in which the FIFO 52W interfaces a main signal frame received through an up optical transmission line 2_UW from the antenna end device 3W, and the FIFO 52P interfaces a main signal frame received through an up optical transmission line 2_UP from the antenna end device 3P for the protection system, so that they transmit the main signal frames for the working system and the protection system to a data generation/termination unit (not shown) at the next stage.
It is to be noted that the FIFO 52W and 52P are composed of a write controller (WC) 52_1, a memory (RAM) 52_2 and a read controller (RC) 52_3, respectively, in which the write controller 52_1 writes received data in the memory at a predetermined address, and the read controller 52_3 reads out data from the memory 52_2 according to the clocks of its own station end device 50, whereby the main signal frame from the optical transmission line 2 is changed to the main signal frames for the working system and the protection system at the station end device 50 to be provided as an output.
On the other hand, there has been proposed a W-CDMA radio base station and delay time correction method therefor as follows: In a radio device of the 0-system, an input signal is divided into two, and a signal is provided to a delay time detection control circuit. Also, an output signal is divided into two, and a signal is provided to the circuit. In the circuit, the amplitude fluctuation pattern is compared with the amplitude fluctuation pattern, matching timing difference is detected as a delay time with respect to, and a delay-adjusting time in the device is controlled so that the delay time is set at a set value. Similarly, in the 1-system, a delay-adjusting time in a radio device is controlled (see patent document 1).
Also, there has been proposed a W-CDMA wireless base station and delay time difference correcting method therefor as follows: At the time of IPDL (individual physiological data logger), BB (base band) signals are outputted from idle circuits, in a non-transmission state. A carrier is modulated with a transmission signal of a system 0 in an RF (radio frequency) circuit, is outputted as an RF signal, is distributed by a directional coupler, and is detected by a detector and inputted into a control circuit. Similarly, a transmission signal of a system is inputted into the circuit through an RF circuit, a directional coupler and a detector. In the circuit, delay time deviation is detected on the basis of the rise edges of transmission signal of a system 0 and a transmission signal of a system 1, control signals are respectively outputted to delay adjusting circuits to correct the delay time deviation. In the circuits, the delay time is adjusted (see patent document 2).
Also, there has been proposed a transmission diversity delay correcting system, which uses a TSTD system including a system 0, having a transmitting and receiving function and a system 1 having a transmitting and receiving function as well, is equipped with a transmission system means which processes transmit data and sends an RF signal and a reception system means, which receives and processes the RF signal and outputs receive data for the 0-system or 1-system respectively; and the transmission system means of the 0-system or 1-system and the reception system means of the 1-system or 0-system are combined and the delay quantity of a delay-adjusting circuit which is provided for the transmission system means of the 0-system or 1-system is shifted, until the receive data of the 1-system or 0-system can be decoded (see patent document 3).
Also, there has been proposed a delay amount/transmission level setting system is bidirectional communicating system as follows: The center station measures the reciprocating propagation delay amount of signals when the subscriber station starts the operation and sets the transmission delay amount of the subscriber station so as to make the measured reciprocating propagation delay amount be equal to the system delay amount of a fixed value to the subscriber station. When the link changeover from an active system to a standby system is generated by the generation of a fault in a relay transmission line, the center station measures the reciprocating propagation delay amount of the signals to one subscriber station after the link changeover and resets the transmission delay amount of all the subscriber stations connected to the repeater station altogether based d on a difference from the reciprocation propagation delay amount of the signals to the entire subscriber station before the link changeover (see patent document 4).
Also, there has been proposed a phase adjusting device as follows: At the time of automatic phase adjustment, a switching signal is supplied to a signal integrating board, a dummy integrating board, and a phase adjusting circuit of a control station, and a switching signal is supplied to a signal integrating board, a dummy integrating board, and a control circuit of a radio base station. As the result, signal integrating boards are switched to dummy integrating boards. Then, the current system is equivalently switched to the stand-by system with respect to the operation of the whole of a device. A down control signal as phase adjustment data is sent from a signal generating circuit by the control of a phase adjusting circuit and is supplied to both of signal integrating boards and dummy integrating boards (see patent document 5).
Also, there has been proposed a system delay correcting circuit as follows: A trigger use pulse which is generated is supplied to variable delaying circuits through a directional coupler and a dual receiver, as an artificial question signal, through an artificial question signal generating circuit. An artificial question pulse outputted from the circuits is sent out as an artificial answer signal through a modulated pulse generating circuit and a circulator. Apart of this artificial answer signal is supplied to a gate circuit, as time information of an artificial answer pulse through a directional coupler and a time detecting circuit. The circuit stops counting of a counter circuit, and measures a system delay. Also, in an averaging circuit, a drift is averaged. A controlled variable adjusting circuit drives the variable delaying circuits by using a difference between a system delay measured value and a prescribed value from a deciding circuit, as a correction quantity, and outputs a signal for varying the delay quantity (see patent document 6).
Also, there has been proposed a phase matching control system including a transmitter for transmitting same data; and a receiver for receiving the data; each of transmission sections in the transmitter includes frame generation transmission sections for generating frames with a period twice a maximum prediction delay or over, inserting phase information indicative the phase of each frame to the frame, and each of the reception sections includes phase matching sections for receiving the frame and the phase information, matching phases of the corresponding frames in a plurality of the transmission lines on the basis of the phase information and providing an output (see patent document 7).
Also, there has been proposed a phase difference delay control system as follows: between the reference position and the terminal, a first interface part and a second interface part are provided with a clock transfer part, respectively, for adding an overhead containing phase information for phase matching of a redundant signal and transmitting it to a transmission line, or for eliminating the overhead from a signal from the transmission line and transmitting the signal to the terminal or the reference position. A changing amount of phase difference between writing and reading in one clock transfer part out of the clock transfer parts operating in response to a reference clock signal is informed to the other clock transfer part. The changing amount is added to or subtracted from initial phase difference when the phase difference is initialized (see patent document 8).
Also, there has been proposed a frame synchronizing device in mobile communication system as follows: A transmission delay time calculating means sends a message for transmission time measurement to each base station and statistically calculate the transmission time to the base station from its response time and a frame synchronism control means sends a frame synchronism message including its transmission time information to each base station. Each base station having received the frame synchronism message generates frame timing by a frame timing generating means by using the transmission time information to synchronize the frame timing among base stations connected by the IP network (see patent document 9).    [patent document 1] Japanese Patent Application Laid-open No. 2003-258694    [patent document 2] Japanese Patent Application Laid-open No. 2003-158774    [patent document 3] Japanese Patent Application Laid-open No. 2002-374193    [patent document 4] Japanese Patent Application Laid-open No. 10-285570    [patent document 5] Japanese Patent No. 3001204    [patent document 6] Japanese Patent Application Laid-open No. 63-243892    [patent document 7] Japanese Patent Application Laid-open No. 2003-244085    [patent document 8] Japanese Patent Application Laid-open No. 2003-244107    [patent document 9] Japanese Patent Application Laid-open No. 2000-324535
In the prior art example shown in FIG. 8, a phase synchronization (adjustment) between the working main signal frame and the protection main signal frame respectively outputted from the FIFOs 52W and 52P in the station end device 50 is performed not with the main signal frames themselves, but with a control signal (not shown) returned through the station end device 50—the optical transmission line 2—the antenna end device 3—the station end device 50. Therefore, such a phase adjustment is not performed by observing the phase deviation (shift or displacement) between the working and the protection main signal frame themselves, so that a phase deviation may occur between the working main signal frame and the protection main frame outputted by the station end device 50.